a) Field of the Invention
The invention relates to an apparatus for placing surgical staples which can be moved one after another from a staple support onto a lower die and can be deformed there using an upper die, by being able to lower and further adjust the upper die onto the particular staple to be placed situated on the lower die, wherein the staple is deformed by bending around the lower die and then separated from the lower die using an ejector which stands in a first position during the deformation process when it is not in contact with the particular staple to be implanted, and which can be moved into a second position in the direction of the implanted staple after the deformation process to push the staple from the lower die.
b) Description of the Prior Art
In known surgical staplers (U.S. Pat. No. 3,873,016, U.S. Pat. No. 4,109,844, U.S. Pat. No. 4,202,480) it is often necessary for the surgeon to move the apparatus a certain distance forwards or backwards after implanting a staple to thus release the staple from the lower die. However, this measure disturbs many surgeons because the horizontal movement of the apparatus required for this is in the opposite direction to the mainly vertical course of movement usual for staples.
Apparatus for which the surgeon need only concentrate on the precise placing of the staples during use and is not distracted further by movements of the apparatus which are also required for ejecting the particular implanted staple from the lower die, is therefore preferred. Apparatus of this type may be easily lifted vertically from the wound after placing a staple, when the staple has been ejected automatically from the apparatus or from the lower die.
An apparatus is known from European patent 0 124 556, the lower die of which can be mechanically adjusted so that after placing a staple it is withdrawn from the region between staple bar and wound, wherein the staple moves away from the lower die and is released. However, this apparatus has complicated and troublesome mechanics. A movable lower die also has the disadvantage that the precision of staple deformation required is no longer possible even at the lowest and mostly unavoidable deviations of the actual position of the lower die from its theoretical position relative to the upper die.
A further possibility for releasing the staple from the lower die is described in European application 0 324 166. In this previously known apparatus, a leaf spring serving as ejector presses constantly on the bar of the staple to be implanted and implanted staple, so that the leaf spring pushes the staple from the lower die as soon as the upper die is removed from its position with the staple. However, this solution has the disadvantage that forces act on the staple to be placed as a result of the ejector leaf spring even before and during the staple deformation, and these forces may lead to the staple being adjusted, for example by tilting from its intended position and then it is no longer possible to implant it in an exactly aligned position. It will therefore be necessary to guide the staples in several planes by means of additional precision components, and this is associated with a correspondingly high effort.
To this end an improvement will be an apparatus in which the ejector in a first position does not contact the particular staple to be implanted before and during the deformation process, and which can be adjusted into a second position in the direction of the implanted staple after deformation of the staple to push or eject the staple from the lower die.
In a known apparatus of this type (U.S. Pat. No. 4,523,707), the ejector is adjusted between two positions on an arc-shaped path, wherein it is laterally displaced into the second position mentioned when moving-in to thus bring ejector tools to rest against the staple situated on the lower die. However, the movement of the ejector on a curved path and the displacement movement of the ejector tools which is lateral relative to the curved path necessitate complex designs and troublesome control and adjustment mechanisms for the ejector. Since tools thereof engage at the staple bar, there are also unfavourable leverages in the region between the surfaces of the wound to be stapled and the lower die, so that there may be excessive tilting during the ejection process and hence undesirable movements of the staple in the tissue.
In contrast the invention is to propose an apparatus, the ejector system of which operates according to a simple, reliable and inexpensive principle and by means of which the staple may be pushed without difficulty and without a tendency to tilt from the lower die.